package org.ahmadsoft.stream;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;
import java.util.ArrayList;

import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.antlr.stringtemplate.StringTemplate;
import org.antlr.stringtemplate.StringTemplateGroup;
import org.antlr.stringtemplate.language.DefaultTemplateLexer;

import sun.misc.BASE64Encoder;

/**
 * A servlet that implements a standard n-Tier architecture with
 * remote calls between the application (ejb) and web (servlet) 
 * tiers.
 * 
 * @author Amin Ahmad
 */
public class RemoteEjbServlet extends HttpServlet {

	private StringTemplateGroup presidentTemplate;

	public void init(ServletConfig config) throws ServletException {
		InputStreamReader in = new InputStreamReader(getClass().getClassLoader().getResourceAsStream("org/ahmadsoft/stream/template/presidents.stg"));
		presidentTemplate = new StringTemplateGroup(in,	DefaultTemplateLexer.class);
	}

	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		long a = System.nanoTime();

		President[] presidents = getPresidents();

		StringTemplate header = presidentTemplate.getInstanceOf("header");
		PrintWriter out = new PrintWriter(new OutputStreamWriter(response
				.getOutputStream()));
		
		long b = System.nanoTime();
		out.print(header.toString());
		
		BASE64Encoder base64 = new BASE64Encoder();
		long c = -1;
		for (President p : presidents) {
			if (c == -1)
				c = System.nanoTime();
			StringTemplate line = presidentTemplate.getInstanceOf("line");
			line.setAttribute("president", p);
			line.setAttribute("thumbnail", base64.encode(p.getThumbnail()));
			out.print(line.toString());
		}

		long d = System.nanoTime();
		StringTemplate footer = presidentTemplate.getInstanceOf("footer");
		footer.setAttribute("timeByte1", Long.valueOf(b-a));
		footer.setAttribute("timeRow1" , Long.valueOf(c-a));
		footer.setAttribute("timeClose", Long.valueOf(d-a));
		out.print(footer.toString());
		out.close();
	}

	/**
	 * Retrieves a list of presidents. In a standard n-tier architecture, this
	 * method would call to the application (ejb) tier to retrieve this
	 * information.
	 * 
	 * @return
	 */
	private President[] getPresidents() {
		ArrayList presidents = new ArrayList();
		try {
			Class.forName("com.mysql.jdbc.Driver");
			Connection connection = DriverManager
					.getConnection("jdbc:mysql://localhost/mysql?user=root&password=foo&defaultFetchSize=10&useCursorFetch=true");
			Statement stmt = connection.createStatement();
			stmt.setFetchDirection(ResultSet.FETCH_FORWARD);
			ResultSet rs = stmt.executeQuery("SELECT * FROM PRESIDENT");
			while (rs.next()) {
				President p = new President();
				p.setName(rs.getString("TX_NAME"));
				p.setOfficeStart(rs.getDate("DT_OFFICE_ST"));
				p.setOfficeEnd(rs.getDate("DT_OFFICE_END"));
				p.setSummary(rs.getString("TX_SUMMARY"));
				p.setThumbnail(Util.getBytes(rs.getBlob("BL_THUMBNAIL")));
				presidents.add(p);

			}
			connection.close();
			President[] ssPresidents = (President[]) presidents
					.toArray(new President[0]);

			// simulate serialization/deserialization.

			ByteArrayOutputStream baos = new ByteArrayOutputStream();
			ObjectOutputStream oos = new ObjectOutputStream(baos);
			oos.writeObject(ssPresidents);
			oos.close();

			ByteArrayInputStream bais = new ByteArrayInputStream(baos
					.toByteArray());
			ObjectInputStream ois = new ObjectInputStream(bais);
			ssPresidents = (President[]) ois.readObject();
			return ssPresidents;
		} catch (Exception e) {
			e.printStackTrace();
			return new President[0];
		}
	}

}